Monthly Archives: October 2018

Equipment, Procedures

Trends In IVC Filter Placement And Retrieval

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Yesterday, I reviewed a paper that highlighted a single-institution experience for IVC filter usage. Today, let’s look at a much larger pool of data.

Placement of a filter in the inferior vena cava (IVC) is one of the many tools for managing pulmonary embolism. There was a significant increase in filter placement during the 1990s and 2000s due to a broadening of the indications for its use.  There has been continuing debate over the complications and efficacy of use of this device.

A paper from NYU Langone Health in New York City, the Harvey L. Neiman Health Policy Institute, and Georgia Institute of Technology School of Economics looked a long-term trends in IVC filter use in the Medicare population. They scanned a Centers for Medicare and Medicaid Services (CMS) database over the 22 year period from 1994 to 2015. They specifically analyzed trends in insertion, removal, placement setting, and specialty of the inserting physician.

Here are the factoids:

  • 2008 seemed to be the heyday of IVC filter insertion. Rates nearly tripled by 2008, but have declined about 40% since then (see below). Pay attention to the retrieval rates.

  • Overall, filters were most commonly placed by radiologists, followed by surgeons and cardiologists. Here’s the diagram above broken down by specialty.

  • This chart shows the market share of each specialists inserting IVC filters during the study period. Of note, radiologists continue to increase and surgeons are decreasing.

Bottom line: This study shows some interesting data, but can’t be completely applied to trauma patients because it focuses on Medicare recipients. But the trends are valid. IVC filter use peaked in 2008 and has been declining ever since. Radiologists place more filters than other specialties, and their market share continues to increase.

Most disturbing is the low filter retrieval rate, similar to what was seen in yesterday’s post. Device manufacturers recommend removal of most filters, but timeframes are not specified. The real bottom line is that we have an indwelling device which works well in very limited situations only, can cause long term complications, and that we frequently forget to remove. It behooves all trauma professionals to develop strict guidelines for both use and removal.

Reference: National Trends in Inferior Vena Cava Filter Placement and Retrieval Procedures in the Medicare Population Over Two Decades. J Am Coll Radiol 15:1080-1086, 2018.

Procedures

The IVC Filter In Trauma: Why?

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The inferior vena cava (IVC) filter has been around in one form or another for over 40 years. One would think that we would have figured everything about it out by now. But no!  The filter has evolved through a number of iterations and form factors over the years. The existing studies, in general, give us piecemeal information on the utility and safety of the device.

One of the major innovations with this technology came with the development of a removable filter. Take a look at the product below. Note the hook at the top and the (relatively) blunt tips of the feet. This allows a metal sheath to be slipped over the filter while in place in the IVC. The legs collapse, and the entire thing can be removed via the internal jugular vein.

ivc-filter-complications1

The availability of the removable filter led the American College of Chest Physicians to recommend their placement in patients with known pulmonary embolism (PE) or proximal deep venous thrombosis (DVT) in patients with contraindications to anticoagulation. Unfortunately, this has been generalized by some trauma professionals over the years to include any trauma patients at high risk for DVT or PE, but who don’t actually have them yet.

One would think that, given the appearance of one of these filters, they would be protective and clots would get caught up in the legs and be unable to travel to the lungs as a PE. Previous studies have taught us that this is not necessarily the case. Plus, the filter can’t stop clots that originate in the upper extremities from becoming an embolism. And there are quite a few papers that have demonstrated the short- and long-term complications, including clot at and below the filter as well as post-phlebitic syndrome in the lower extremities.

A study from Boston University reviewed their own experience retrospectively over a 9 year period. This cohort study looked at patients with and without filters, matching them for age, sex, race, and injury severity. The authors specifically looked at mortality, and used four study periods during the 9 year interval.

Here are the factoids:

  • Over 18,000 patients were admitted during the study period, resulting in 451 with an IVC filter inserted and 1343 matched controls
  • The patients were followed for an average of 4 years after hospitalization
  • Mortality was identical between patients with filters vs the matched controls

dvt-study

  • There was still no difference in mortality, even if the patients with the filter had DVT or PE present when it was inserted
  • Only 8% ever had their “removable” filter removed (!)

Bottom line: Hopefully, it’s becoming obvious to all that the era of the IVC filter has come and gone. There are many studies that show the downside of placement. And there are several (including this one) that show how forgetful we are about taking them out when no longer needed. And, of course, they are expensive. But the final straw is that they do not seem to protect our patients like we thought (hoped?) they would. It’s time to reconsider those DVT/PE protocols and think really hard about whether we should be inserting IVC filters in trauma patients at all.

Tomorrow: a look at trends in filter insertion and retrieval.

Related post:

Reference: Association Between Inferior Vena Cava Filter Insertion
in Trauma Patients and In-Hospital and Overall Mortality. JAMA Surg, online ahead of print, September 28, 2016.